Service with full state honours concludes 10 days of mourning for anti-apartheid campaigner and Nelson Mandela's ex-wife.

South Africa has laid to rest anti-apartheid icon Winnie Mandela with full state honours at a stadium funeral in Soweto.

The ex-wife of the country's former President Nelson Mandela died earlier this month at the age of 81.

Tens of thousands of mourners burst into loud cheers as the coffin carrying her remains was wheeled into the stadium, less than 2km from her home on Saturday.

The coffin draped with the multi-coloured South African flag was placed in the middle of the 37,500-seat stadium in front of a stage, decked in white and yellow flowers.

Mourners dressed in the colours of the ruling African National Congress (ANC), as well those of the radical opposition Economic Freedom Fighters (EFF), sang "there's no one like Winnie", an adapted popular liberation struggle song.

The ceremony concludes 10 days of national mourning during which time thousands of South Africans have paid tribute to the "mother of the nation" at her Soweto home and elsewhere.

'Go well, Mama'

Winnie Mandela, who died in Johannesburg on April 2 after a long illness, has been celebrated for helping keep Nelson Mandela's dream of a non-racial South Africa alive while he was behind bars for 27 years.

"She was one of the most profound leaders of the ANC," said 53-year-old mourner Brian Magqaza. "She fought from beginning to the end. Go well, Mama."

EFF supporter Mufunwa Muhadi, 31, said "Mama fought for our freedom. It is important to honour her and continue the fight."

South Africa's President Cyril Ramaphosa, who took office two months ago, is leading the mourners at the pre-burial service in Soweto's Orlando stadium.

Two former South African presidents, Jacob Zuma and Thabo Mbeki, are also attending the funeral.

Mourners booed when the presence of scandal-tainted Zuma was publicly acknowledged.

Foreign dignitaries at the funeral include the leaders of Namibia, Swaziland and the Republic of Congo, as well as American civil rights activist Jesse Jackson.

"She is truly the mother of South Africa," Jackson said on Friday.

The township of Soweto is hugely symbolic in South Africa as it became a crucible of black resistance against white minority rule, which ended with elections in 1994.

Winnie Mandela refused to follow many other struggle-era politicians who moved from townships like Soweto to formerly white-only suburbs after the end of apartheid.

Instead, she remained embedded in the community where she met Nelson Mandela who became the first black president of democratic South Africa, but she at a bus stop in 1957.

After the formal service, Winnie Mandela's body will be buried 40km north of Soweto, at a privately run graveyard in Johannesburg's upmarket Fourways suburb where two of her great-grandchildren are also buried.

'Symbol of resistance'

The funeral closes the final chapter in the history of a woman who was exalted for her fearless defiance of apartheid rule but also implicated in violence and corruption in later life.

In 1991, she was convicted of kidnapping and being an accessory in the assault of a 14-year-old boy and was more generally accused of overseeing violence in black townships.

In 2003, she was found guilty of fraud.

But her controversial reputation has been largely brushed aside in the wake of her death with tributes to her bravery, independence and integrity dominating public commemorations.

The UN staged a special memorial sitting at its New York headquarters on Friday to mark her passing.

Nomvula Mokonyane, South Africa's communications minister told AFP news agency that Winnie should not only be remembered for "mistakes or the casualties of the struggle".

In old age, Winnie Mandela emerged as a respected elder who was feted as a living reminder of her late husband - and of the long and celebrated struggle against apartheid.

Most of her 38-year marriage to Nelson was spent apart, leaving her to raise their two daughters alone as she kept his political dream alive.

But when Nelson Mandela died in 2013, it emerged he had left Winnie nothing in his will.

On Saturday, a 21-gun salute will be fired and a full honour guard is expected to escort Winnie's remains to her final resting place.